Module 3 - cells and tissue- Membrane structure general overview

What are the factors affecting membrane fluidity?

Lipid composition, unsaturated fatty acids conc , temp , cholesterol conc

How does Lipid composition affect membrane fluidity?

Shorter fatty acid-less rigid-remain fluid (increases)

How does the presence of unsaturated fatty acids increase membrane fluidity?

The double bond introduces kinks in the fatty acid so more difficult to pack.

Does high-temperature increase or decease membrane fluidity?

Increases

How does cholesterol affect membrane fluidity?

It acts as a fluid buffer. It makes it more fluid in very cold temperatures, by not allowing the membrane to come in too close. In too warm temperatures it decreases fluidity.

Are phospholipids amphipathic? What does this mean

YES- both hydrophilic and hydrophobic.

What does single chain and water aggregate to ?

monolayer and micelle

What does double chain and water aggregate to ?

monolayer, bilayer and liposomes

How do micelle form?

phospholipds have one fatty acids (conical)

How do Bilayers form ?

when phospholipids have two fatty acids (cylindrical)

How do spherical bilayers form ?

when phospholipds at the ends curve round to protect themselves with in the cell.

What are the major functions on the cell membrane ?

1.Keep toxins out of the cell

2. Control movement of water and macromolecules

3.Provide structural support and protection

4.Provide a site for catalysis

5.Establish chemical and electrical gradients

6.Cell-cell recognition

7.Cell signalling

8.Plasma membrane of organelles separates incompatible biochemical processes

Describe the membrane structure ?

Fluid/ elastic phospholipid bilayer. Has small proteins floating in it and small amounts of carbohydrates giving a mosaic appearance.

What are the 4 types of phospholipids?

phosphatidyl serine, phosphatidyl ethanolamine, phosphatidyl choline, Sphingomyelin